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Quantitative Analysis of ″Polymer-Balls″ in Aqueous Solutions by Small-Angle Neutron Scattering
Shibayama, Mitsuhiro,Okabe, Satoshi,Nagao, Michihiro,Sugihara, Shinji,Aoshima, Sadahito,Harada, Tamotsu,Matsuoka, Hideki The Polymer Society of Korea 2002 Macromolecular Research Vol.10 No.6
The quantitative analysis of polymer micelles consisting of amphiphilic block copolymers was carried out by small-angle neutron scattering (SANS). The block copolymers, made of poly(2-ethoxyethyl vinyl ether-b-2-hydroxyethyl vinyl ether)(poly(EOVE-b-HOVE)), exhibited a sharp morphological transition from a homogeneous solution to a micelle structure with increasing temperature. This transition is accompanied by a formation of spherical domains of poly(EOVE) with a radius around 200 $\AA$. The variations of the size and its distribution of the domains were investigated as a function of polymer concentration and temperature. The validity of SANS analysis, including the wavelength- and incident-beam-smearing effects of the SANS instrument, was examined with a pre-calibrated polystyrene latex.
Iwamoto, Takuro,Doi, Yuya,Kinoshita, Keita,Takano, Atsushi,Takahashi, Yoshiaki,Kim, Eunhye,Kim, Tae-Hwan,Takata, Shin-ichi,Nagao, Michihiro,Matsushita, Yushu American Chemical Society 2018 Macromolecules Vol.51 No.17
<P>Conformations of highly purified ring polystyrene, R-70, with the molar mass of 70 kg/mol, in a good solvent and in linear polymer homologue matrices were examined by small-angle neutron scattering (SANS) measurements. The radii of gyration <I>R</I><SUB>g</SUB> of R-70 were estimated by the Guinier’s approximation from the SANS profiles obtained, and the polymer volume fraction Φ dependence of <I>R</I><SUB>g</SUB><SUP>2</SUP> was discussed. In deuterated toluene as a good solvent, R-70 exhibits the <I>R</I><SUB>g</SUB><SUP>2</SUP> ∼ Φ<SUP>-0.29±0.01</SUP> dependence at high Φ above the overlap volume fraction, Φ<SUB>0</SUB>* (i.e., 1 < Φ/Φ<SUB>0</SUB>* < 20). This exponent −0.29 shows stronger Φ dependence than that for semidilute solutions of linear polymers, −0.25, predicted from the scaling theory, suggesting that the ring expands more sensitively than linear chains when Φ decreases in semidilute regime. In contrast, the Φ dependence of <I>R</I><SUB>g</SUB><SUP>2</SUP> of R-70 is evidently weaker than that of the recent simulation for ring polymer solutions (<I>R</I><SUB>g</SUB><SUP>2</SUP> ∼ Φ<SUP>−0.59</SUP>) by Reigh et al. This difference is thought to originate from the difference in the ring chain length; i.e., the simulation treated much longer rings than the ring adopted in this study. Therefore, it is expected that the exponent −0.29 for the ring polymer solutions obtained in this study is not a limiting value but is a transit one toward higher Φ/Φ<SUB>0</SUB>* region. The size of R-70 is also increased when the ring was diluted with linear polystyrenes. However, the degree of expansion of the rings in linear polymer matrices is considerably lower than that in toluene solutions. Moreover, the molar masses of the linear chains added hardly effect the expansion behavior of the rings. In fact, the dimension of rings gets closer to that of the Gaussian rings as a larger amount of linear chains is added.</P> [FIG OMISSION]</BR>